Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!hplabs!hpcc05!col!hpldola!hp-lsd!davem
From: davem@hp-lsd.COS.HP.COM (Dave K. Martin)
Newsgroups: sci.electronics
Subject: Re: Nasty TV interference
Message-ID: <25150012@hp-lsd.COS.HP.COM>
Date: 10 Jan 91 20:04:21 GMT
References: <5787@uafhp.uark.edu>
Organization: HP Logic Systems Division - ColoSpgs, CO
Lines: 36

Are you operating your Amiga with the cover off (A2000 & 3000 models) or have 
the internal metal RF-shields been removed (A-1000 & A-500 models)?

Are you using external disk drives with covers or shielding removed?  
Do you have unshielded (ribbon cable) extension cables for your disk drives?

Does your printer cable have shielding?  Is it the printer itself that is 
creating the interference?

Are you using the original keyboard and mouse?  The originals had ferrite 
core rf filters on the cables (the big ugly shrink-wrapped things next to the 
plugs).

Position may be a factor also.  Is the Amiga right next to the TV or directly
opposite on the other side of a wall?  Moving one or the other may help here.

I have an Amiga 2000 and an Amiga 1000 on the same desk with a TV about 8" 
above the A-1000 and have no problems at all.  The Epson printer can cause 
havoc with the TV but then it has a 25' unshielded parrallel cable.
I've run the A-2000 without the cover and no noticable interference.  Once I 
had the RF shield off of the A-1000 and the TV was totaly unwatchable.

The external disk drives can induce a pattern on the tv screen simular to the 
workbench screen.  I have an Amiga 1010 and two California Access CA-880's on
my 1000.  The A-1010 has no effect on the TV but both the CA-880's will 
create a ghost image when they are accessed.  I solved this by changing the 
TV lead to a coax and eliminating the matching transformer at the TV.

My guess is that your TV has an inside (rabbit-ears) antenna or a matching 
transformer in the antenna lead.  In either case, they are quite close to the 
Amiga.  Commodore goes to some lengths to keep the RF inside the case from 
getting outside.  All leads in and out have individual ferrite cores on them
and of course the metal shielding around the pc boards.

Hope this has been helpful.  It is not a flame although after re-reading it,  
it sure sounds like one :-).....